fixing iso14443b (issue #103):

- most significant bit of tag data (which happens to be the sign bit)
had been dropped when snooping (FPGA change)
- avoid trying to decode both tag and reader data when snooping (we don't
have the time to do so).

diff --git a/armsrc/iso14443b.c b/armsrc/iso14443b.c
index 8add8f9c3eb27b4a9a5108d55e4280c01407c8fa..d659558672f2a2a3c7901560744942a23dd7c64c 100644 (file)
--- a/armsrc/iso14443b.c
+++ b/armsrc/iso14443b.c
@@ -158,7 +158,6 @@ static int Handle14443UartBit(int bit)
 {
        switch(Uart.state) {
                case STATE_UNSYNCD:
-                       LED_A_OFF();
                        if(!bit) {
                                // we went low, so this could be the beginning
                                // of an SOF
@@ -272,8 +271,7 @@ static int Handle14443UartBit(int bit)
                        break;
        }
 
-       // This row make the error blew circular buffer in hf 14b snoop
-       //if (Uart.state == STATE_ERROR_WAIT) LED_A_OFF(); // Error
+       if (Uart.state == STATE_UNSYNCD) LED_A_OFF();
 
        return FALSE;
 }
@@ -1054,17 +1052,17 @@ void ReadSTMemoryIso14443(uint32_t dwLast)
 //-----------------------------------------------------------------------------
 /*
  * Memory usage for this function, (within BigBuf)
- * 0-4095 : Demodulated samples receive (4096 bytes) - DEMOD_TRACE_SIZE
- * 4096-6143 : Last Received command, 2048 bytes (reader->tag) - READER_TAG_BUFFER_SIZE
- * 6144-8191 : Last Received command, 2048 bytes(tag->reader) - TAG_READER_BUFFER_SIZE
- * 8192-9215 : DMA Buffer, 1024 bytes (samples) - DEMOD_DMA_BUFFER_SIZE
+ * Last Received command (reader->tag) - MAX_FRAME_SIZE
+ * Last Received command (tag->reader) - MAX_FRAME_SIZE
+ * DMA Buffer, 1024 bytes (samples) - DMA_BUFFER_SIZE
+ * Demodulated samples received - all the rest
  */
 void RAMFUNC SnoopIso14443(void)
 {
        // We won't start recording the frames that we acquire until we trigger;
        // a good trigger condition to get started is probably when we see a
        // response from the tag.
-       int triggered = TRUE;
+       int triggered = TRUE;                   // TODO: set and evaluate trigger condition
 
        FpgaDownloadAndGo(FPGA_BITSTREAM_HF);
        BigBuf_free();
@@ -1109,7 +1107,10 @@ void RAMFUNC SnoopIso14443(void)
        FpgaSetupSscDma((uint8_t*) dmaBuf, DMA_BUFFER_SIZE);
        uint8_t parity[MAX_PARITY_SIZE];
        LED_A_ON();
-               
+
+       bool TagIsActive = FALSE;
+       bool ReaderIsActive = FALSE;
+       
        // And now we loop, receiving samples.
        for(;;) {
                int behindBy = (lastRxCounter - AT91C_BASE_PDC_SSC->PDC_RCR) &
@@ -1136,49 +1137,56 @@ void RAMFUNC SnoopIso14443(void)
 
                samples += 2;
 
-               if(Handle14443UartBit(ci & 1)) {
-                       if(triggered && tracing) {
-                               GetParity(Uart.output, Uart.byteCnt, parity);
-                               LogTrace(Uart.output,Uart.byteCnt,samples, samples,parity,TRUE);
-                       }
-                       if(Uart.byteCnt==0) Dbprintf("[1] Error, Uart.byteCnt==0, Uart.bitCnt=%d", Uart.bitCnt);
+               if (!TagIsActive) {                                                     // no need to try decoding reader data if the tag is sending
+                       if(Handle14443UartBit(ci & 0x01)) {
+                               if(triggered && tracing) {
+                                       GetParity(Uart.output, Uart.byteCnt, parity);
+                                       LogTrace(Uart.output,Uart.byteCnt,samples, samples,parity,TRUE);
+                               }
+                               if(Uart.byteCnt==0) Dbprintf("[1] Error, Uart.byteCnt==0, Uart.bitCnt=%d", Uart.bitCnt);
 
-                       /* And ready to receive another command. */
-                       UartReset();
-                       /* And also reset the demod code, which might have been */
-                       /* false-triggered by the commands from the reader. */
-                       DemodReset();
-               }
-               if(Handle14443UartBit(cq & 1)) {
-                       if(triggered && tracing) {
-                               GetParity(Uart.output, Uart.byteCnt, parity);
-                               LogTrace(Uart.output,Uart.byteCnt,samples, samples, parity, TRUE);
+                               /* And ready to receive another command. */
+                               UartReset();
+                               /* And also reset the demod code, which might have been */
+                               /* false-triggered by the commands from the reader. */
+                               DemodReset();
                        }
-                       if(Uart.byteCnt==0) Dbprintf("[2] Error, Uart.byteCnt==0, Uart.bitCnt=%d", Uart.bitCnt);
+                       if(Handle14443UartBit(cq & 0x01)) {
+                               if(triggered && tracing) {
+                                       GetParity(Uart.output, Uart.byteCnt, parity);
+                                       LogTrace(Uart.output,Uart.byteCnt,samples, samples, parity, TRUE);
+                               }
+                               if(Uart.byteCnt==0) Dbprintf("[2] Error, Uart.byteCnt==0, Uart.bitCnt=%d", Uart.bitCnt);
 
-                       /* And ready to receive another command. */
-                       UartReset();
-                       /* And also reset the demod code, which might have been */
-                       /* false-triggered by the commands from the reader. */
-                       DemodReset();
+                               /* And ready to receive another command. */
+                               UartReset();
+                               /* And also reset the demod code, which might have been */
+                               /* false-triggered by the commands from the reader. */
+                               DemodReset();
+                       }
+                       ReaderIsActive = (Uart.state != STATE_UNSYNCD);
                }
 
-               if(Handle14443SamplesDemod(ci, cq)) {
+               if(!ReaderIsActive) {                                           // no need to try decoding tag data if the reader is sending - and we cannot afford the time
+                       if(Handle14443SamplesDemod(ci, cq)) {
 
-                       //Use samples as a time measurement
-                       if(tracing)
-                       {
-                               uint8_t parity[MAX_PARITY_SIZE];
-                               GetParity(Demod.output, Demod.len, parity);
-                               LogTrace(Demod.output, Demod.len,samples, samples, parity, FALSE);
-                       }
-                       triggered = TRUE;
-                       LED_A_OFF();
-                       LED_B_ON();
+                               //Use samples as a time measurement
+                               if(tracing)
+                               {
+                                       uint8_t parity[MAX_PARITY_SIZE];
+                                       GetParity(Demod.output, Demod.len, parity);
+                                       LogTrace(Demod.output, Demod.len,samples, samples, parity, FALSE);
+                               }
+                               triggered = TRUE;
+                               LED_A_OFF();
+                               LED_B_ON();
 
-                       // And ready to receive another response.
-                       DemodReset();
+                               // And ready to receive another response.
+                               DemodReset();
+                       }
+                       TagIsActive = (Demod.state != DEMOD_UNSYNCD);
                }
+
                WDT_HIT();
 
                if(!tracing) {

diff --git a/fpga/fpga_hf.bit b/fpga/fpga_hf.bit
index 20fb2bd4401254d899d6273451bfccbd827f562b..53078a782422c09596f006d95c85ae45da20072d 100644 (file)
Binary files a/fpga/fpga_hf.bit and b/fpga/fpga_hf.bit differ

diff --git a/fpga/hi_read_rx_xcorr.v b/fpga/hi_read_rx_xcorr.v
index dece2db3195844ce9ce2d371d09a1ff7df0069bf..ec6583b273f0910acb8fe58b59b5857291123ac3 100644 (file)
--- a/fpga/hi_read_rx_xcorr.v
+++ b/fpga/hi_read_rx_xcorr.v
@@ -99,8 +99,10 @@ end
 reg [5:0] corr_i_cnt;
 reg [5:0] corr_q_cnt;
 // And a couple of registers in which to accumulate the correlations.
-reg signed [15:0] corr_i_accum;
-reg signed [15:0] corr_q_accum;
+// we would add at most 32 times adc_d, the result can be held in 13 bits. 
+// Need one additional bit because it can be negative as well
+reg signed [13:0] corr_i_accum;
+reg signed [13:0] corr_q_accum;
 reg signed [7:0] corr_i_out;
 reg signed [7:0] corr_q_out;
 
@@ -114,12 +116,13 @@ begin
     begin
         if(snoop)
         begin
-            corr_i_out <= {corr_i_accum[12:6], after_hysteresis_prev};
-            corr_q_out <= {corr_q_accum[12:6], after_hysteresis};
+                       // highest 7 significant bits of tag signal (signed), 1 bit reader signal:
+            corr_i_out <= {corr_i_accum[13:7], after_hysteresis_prev};
+            corr_q_out <= {corr_q_accum[13:7], after_hysteresis};
         end
         else
         begin
-            // Only correlations need to be delivered.
+            // highest 8 significant bits of tag signal
             corr_i_out <= corr_i_accum[13:6];
             corr_q_out <= corr_q_accum[13:6];
         end